Storm Time Variation of Radiative Cooling by Nitric Oxide as Observed by TIMED‐SABER and GUVI

Abstract

The variation of O/N2 (reference to N2 column density 1017 cm−2) and nitric oxide radiative emission flux exiting the thermosphere have been studied over the Northern Hemisphere during the superstorm event of 7–12 November 2004. The data have been obtained from Global Ultraviolet Imager (GUVI) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the National Aeronautics and Space Administration (NASA)'s Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite. The NO radiative flux is observed to show an anti‐correlation with O/N2 on a global scale. Both NO radiative flux and O/N2 ratio show equatorward motion with maximum penetration in western longitude sectors. A local variation of O, O2, and N2 densities have been calculated using NRLMSISE‐00 model over a midlatitude location (55°N,180°E). On a local scale, model calculated O/O2 and O/N2 ratios are found to follow the observations made by GUVI. The collisional excitation of NO with atomic oxygen is the most dominant process for the total cooling rate. The SABER‐retrieved NO cooling rate (CR) at a local site suggests an enhancement during the storm period with the peak emission rate closely correlated to the progression of the storm. The peak emission altitude of NO CR moves upward during the main phase of the storm. The NO abundance has been calculated by using cooling rate and Nitric Oxide Empirical Model (NOEM) model. Both these suggest a vary large (3–15 times) increase in NO density during the storm, which is required to account the changes in NO radiative flux. A similar kind of enhancement in NO abundance is also noticed in Student Nitric Oxide Explorer observations during intense geomagnetic storms.

Understanding the Behaviors of Thermospheric Nitric Oxide Cooling During the 15 May 2005 Geomagnetic Storm

“…Whether NO density enhancement and the upward shifting of the peak cooling rate are due to storm‐induced meridional winds or possible heating of enhanced O is still under dispute. However, more and more observational and numerical simulation studies attributed those behaviors to the transport effect by the storm‐induced meridional winds (Barth, ; Barth et al, , ; Bharti et al, ; Dobbin, Aylward, et al, ; Zhang et al, ). During a geomagnetic storm, the meridional winds transport energy and NO‐enhanced air from high latitudes equatorward near 150 km to produce increased NO density in middle and low latitudes, which in turn diffuses and advects downward to ~110 km.…”

“…The reaction with N( 4 S) is the major sink of NO at all altitudes . During geomagnetic storms, NO converts a large amount of heat energy in the ionosphere‐thermosphere system into 5.3‐μm radiative emission, which is subsequently released into the lower thermosphere and space (Bharti et al, ; Lu et al, ). Thus, NO emission is considered as a “natural thermostat” that contributes to the thermosphere recovery from the effects of a solar geomagnetic storm (Mlynczak et al, , ).…”

“…By analyzing SABER data and 192 interplanetary coronal mass ejections (ICMEs) between 2002 and 2014, Knipp et al () found that shock‐led ICMEs are prone to early and excessive thermospheric NO emission, which indicates higher NO abundance and production. Bharti et al () found that the enhancement of NO cooling rate during the intense geomagnetic storm event of 7–12 November 2004 was closely correlated to the progression of the storm, and the peak NO emission altitude at midlatitudes moves upward during the main phase of the storm. However, recently, Bag () reported that the peak NO volume emission rate showed an equatorial movement with descending peak emission altitude during the November 2004 superstorm.…”

Thermospheric Nitric Oxide Cooling Responses to the 14 December 2020 Solar Eclipse

“…NO emission has much larger variations on shorter timescales and dominates the thermospheric cooling process (Lu et al., 2010; Mlynczak et al., 2003, 2005, 2007, 2010). There are extensive studies focused on NO density and NO infrared cooling responses to geomagnetic storms (e.g., Barth, 2010; Barth et al., 2009; Bharti et al., 2018; Dobbin et al., 2006; Knipp et al., 2017; Lei et al., 2011, 2012; Li et al., 2019; Lu et al., 2010; Mlynczak et al., 2003, 2005, 2007; Richards, 2004; Sheng et al., 2017; Siskind et al., 1989; Zhang et al., 2014), however, the changes of NO concentration and NO infrared cooling during transient solar eclipse events have never been directly observed until now.…”

SABER Observation of Storm‐Time Hemispheric Asymmetry in Nitric Oxide Radiative Emission

“…During geomagnetic storm, a large amount of energy/momentum deposited in magnetosphere‐ionosphere‐thermosphere system creates large variations in density, temperature, and composition over the globe via different processes such as convection, particle precipitation, ionization, direct electric field penetration, ion‐drag forcing, and Joule heating (Bag, 2018a, 2018b; Bag et al., 2014, 2017; Bharti et al., 2018; Burns et al., 2004; Fuller‐Rowell et al., 1994, 1996; Huang et al., 2012; Li et al., 2018, 2019; Lu et al., 2010; Prolss, 1993; Richards, 2004; Richmond & Lu, 2000; Richmond & Roble, 1997; Rout et al., 2019; Verkhoglyadova et al., 2016, 2017a, 2017b, and references therein). Two of the most important processes that affect the thermospheric chemistry and dynamics are the auroral electrons and Joule heating.…”